1. Field of the Invention
The present invention relates to electronic pens (position indicators) which are provided for digitizer systems (coordinate input apparatuses) used as input devices for personal computers and the like.
2. Description of the Related Art
A digitizer system includes a digitizer (tablet) which is a substantially flat pad and which is placed on a personal-computer desk or integrated with a display of a portable personal computer (such as a personal digital assistant (PDA)) and an electronic pen which is held and supported by an operator's hand. While the electronic pen is operated on a position detecting area on the digitizer, the position of the electronic pen in the position detecting area is detected, and the detected position is continuously input as relative or absolute coordinate data to the personal computer or a processor.
A variety of additional input devices are used to input continuous coordinate data which correspond to operations by an operator to personal computers and the like. One input device commonly used is a mouse. Such continuous coordinate data is often used as coordinate data for a cursor on a display screen of a personal computer. Various information (signals) other than the coordinate data may be required to specify a position indicated by the cursor on the display screen or coordinate data which correspond to an image rendered by tracing the trajectory of the cursor.
In the above-described mouse, signals (finger-controlled operation information) generated by operating a switch positioned in the vicinity of the tip of a finger of a hand holding the mouse are output as the foregoing information (signals). Two or more switches may be employed so as to correspond to a plurality of fingers, and signals thus generated may be treated as different pieces of information.
In known electronic pens, different types of switches, which in this case are a switch (pen-down switch) which is turned ON when the entirety of a shaft-shaped casing is pressed against a digitizer and a switch (side switch) which is provided on a lateral side of the shaft-shaped casing and which is turned ON when it is pressed in a direction orthogonal to the axis, are employed to generate signals (finger-controlled operation information) which are detected by the digitizer. These signals are output as different pieces of information (signals).
Generally, a shaft-shaped casing for an electronic pen is formed such that a cross section of the casing is circular or substantially circular. When an operator holds the electronic pen, one cannot ensure that a finger (generally an index finger) operating the side switch is always at an appropriate position relative to the side switch. Actually the operator has to adjust his/her grip on the electronic pen in order to press the side switch properly. When the operator repeatedly alternates between the electronic pen and a different input device such as a keyboard, the operation efficiency is greatly reduced.